2 Stroke

[LPGC]

Looking for others thoughts here really...

I've got a speed boat that I bought a couple of years ago, it has a 3 cylinder 70bhp 2 stroke outboard engine and parts for this engine are now nearly all only available as pattern parts. When I bought it it soon became apparent that the engine needed rebuilding having scored pistons and low compression on one cylinder, etc. I had the block rebored and honed, fitted new pistons (and rings obviously), new bearings, new fuel pump, new top and bottom seals for the crankcase but didn't fit new reed valves (which are mounted on the crank on this engine).

Since the rebuild I've had some ggod times and reliable performance with this boat but now I'm thinking the 2 carbs could do with rebuilding, they leak fuel out of the float chamber vents and the engine is getting less reliable.

I know I could get reliable performance on petrol again by rebuilding the carbs but parts are hard to come by and the boating season is upon me, will take a couple of weeks for rebuild kits to arrive from the States so I've started thinking about converting to LPG! To do so would mean lower running costs obviously, but on top of that it may also mean I don't need to buy an extra petrol tank for my planned trip across Cardigan Bay.

Regards converting the 2 stroke to LPG my concerns are that if I use some sort of lube(s) system(s) to introduce the necessary oil, will that oil then properly lubricate all my new bearings? Has been said before that oil dissolve in petrol has a far better chance of doing so... Has also been said that the air fuel mixture cools the rear of the pistons and that air LPG won't do the same? I'm far less concerned about the latter but would be an expensive mistake!

Thinking about using a decent sized reducer, say R90, with 'tell tale' water flowing through it / a few Flashlube type systems feeding 2 stroke oil into the slight vacuum between mixer and carbs..

Also thought - until I've confirmed reed valves are working properly... if they're not, I might be able to add reed valves from a later 2 stroke outboard between the carbs and crank case...

Thoughts very welcome!

Simon

[Gilbertd]

Not sure a Flashlube type system would deliver sufficient oil. You'd normally be looking at running 40 or 50:1 petrol/oil mix so that would be a considerable quantity of oil compared with the odd drop from a Flashlube system. 2 stroke oil is also usually a lot thicker than Flashlube too. Not sure it would work being pulled in by the vacuum either. With the oil mixed with the petrol it is drawn into the crankcase first where the oil separates out and clings to the bearings before the fuel and air gets forced up through the transfer ports.

It must be a pretty old outboard to need pre-mix anyway, most have a positive lube system and have done for some years.

[Bailes1992]

Could you install a smaller jet in the carb and run a very high ratio of petrol to two stroke oil. Effectively the engine would be running lean so then you could introduce the extra fuel needed with a mixer plate.

[LPGC]

It is an old outboard circa 1982, runs a 50:1 mix. I know a lot of even slightly newer 2 stroke outboards have oil injection but apparently they often go wrong and a lot of owners choose not to trust them (premixing oil instead). Looking at the designs of oil injection systems many seem to only have one outlet into the crankcase, so I would still have concerns about oil reaching all bearings etc running on LPG (perhaps even on petrol) with an oil injected model - no idea how much pressure they use to inject the oil but this will determine how good atomisation is.

I'm fairly confident I could find a way around lube systems not flowing enough, enough lubes enough flow, but that still wouldn't necessarily mean the lube would get around all the bearings etc.

At this stage I'm less concerned about getting the lube into the airflow, more concerned that once in the airflow it will reach all the parts it's supposed to and not just drop out of atomisation and pool at the bottom of the crankcase.. Better atomisation would help in that respect and since better atomisation is obtained using smaller nozzles and higher pressure it would seem a pressurised lube system would work best... When 'winterising' outboards an aerosol spray is used to squirt fogging oil through the carbs into the crankcase, into the cylinders through the plug holes - had wondered about using a pressurised oil reservoir (maybe even a manual pump up garden sprayer) with small outlet jets (better atomisation) in the airflow crank side of the carbs, on/off solenoid(s) in line near the carbs.

I know I could fit a smaller carb jet and run say a 10:1 mix of petrol along with LPG but I'm wondering how little petrol (to dissolve the oil and ensure it reaches all parts) would be needed, indeed if any. I know this would solve the lube issue but it would also make the fueling more complicated.. and I'll still have to wait for the carb bits to arrive and now order extra jets!

Simon

[kbs]

Hi Simon,

Hope you enjoy Cardigan bay - may you get many dolphins!

I've never been North of St Davids, but have had many good trips in the Bristol Channel.

Will the R90 be OK with the water? if you divert the output so that the engine circulates it through the housing, won't the salt (and abraisive silt) wreck the R90? No sure about taking the water fromn the 'tell tale' as this is normally a vent on the way to the main exhaust and if restricted - may not output very much.

On sea cooled (raw water cooled) inboards, the temperature has to be kept below ~60c as the salt water seems to eat metal at a far faster rate above that temperature.
Would the R90 give a better (although much shortened) life if you circulated 'cold' sea water through it?

I suppose the best option would be a heat exchanger so that the sea water cools a 'radiator' and that radiator cools the fresh water resevoir that is cooling the engine (fresh water cooling) but that seems like a lot of work unless you want to collect warm water on the boat for other reasons.

I wanted a little two stroke a few years back for my tender. As they were banned for pleasure use in Euroland, I bought;
1) A little 4 stroke
2) an old two stroke for rebuilding.
Now the b*****s have revoked the ban and you can buy (at least small) two strokes again for pleasure craft! Wasted my money.

No idea about the 2t oil though unless it can be added to the (truly empty) LPG tank and liquid LPG injected into the engine?

[LPGC]

Thanks KBS,

The tell tale is just a jet of water that squirts out the engine so you can see the water pump is still working.. On this engine it's feed is from the very top of the block where there should be at least 5psi of water pressure at all times. There is a thermostat housing but actual thermostats were discontinued before this model year, so the jet is usually only luke-warm but gets a bit hotter if the engine is worked hard. I can fit a slightly wider diameter fitting in the top of the block to let more water through the reducer and plumb a slightly wider diameter tell tale jet to the rear of the boat to squirt post reducer water back into the sea..

Not concerned about reducer life, I'm sure it will corrode etc but if it lasts even half a season I'll be happy.. A quick blast across the bay and back in the boat can use more fuel than my V6 Grand Voyager uses to tow the boat the 180+ miles to the boating place! I might just keep a spare R90 on board, engine gets flushed with tap water after being on the sea anyway.

Wouldn't be able to add oil to the tank, that would definitely be bad news!

Had a mess with the boat engine the other day, had it running (noisily) in the yard with 'headphones' attached for the cooling water (hosepipe fed). It wasn't firing on the bottom cylinder regardless of a good spark and drawing it's fuel from the same area as the other 2 cylinders. Removing the top plug's lead with insulated pliers with the engine running (still half expecting a shock but luckily not getting one) made most difference, the middle plug a bit less difference, the bottom plug no difference at all. The bottom plug looked very clean each time I removed it and the way in which the tell tale output seemed to surge when switching the engine off makes me think the exhaust water jacket is maybe leaking water into the bottom cylinder through it's exhaust port washing the plug. I checked compression on all cylinders and got 125psi on the 2 working cylinders and 120psi on the none working cylinder, I doubt compression is the issue. Other potential problems are that the bottom of the 2 reed valves isn't working, or the bottom crank seal is gone but I fitted new crank case seals when I rebuilt the engine and the bottom of the 2 carbs is drawing as much air as the top carb, so the potential exhaust port issue is looking most likely - This was the one part of the engine I overlooked when rebuilding it, reason being the housing bolts seemed (as expected) truly seized, but I will bite the bullet and take it to bits one day soon, maybe then needing to use bolt extractors on those that shear off etc, probably be one or two to helicoil, might have to fabricate a new exhaust housing if the old one is beyond repair by welding. At least the exhaust housing is a job that can be done without removing the powerhead, anything else mentioned here would need the powerhead off, a pain of a job!

I'll have to get the misfire sorted before anything else, of course. Before I do strip the exhaust cover off I might swap the 2 carbs positions but that means changing all the throttle mechanism around. I know that the carbs need rebuilding, this would just rule out the bottom carb feeding the bottom cylinder with nothing but air out of the list of possibles but I doubt this will be the problem here, I had a good play with the bottom carb including making it flood the engine and still the bottom came out clean! Just thought of something else to try too - I will run the engine for a short time without cooling water, aha! Will just have to fit another new water pump impeller afterwards...

Simon

[kbs]

Hi,

If (whilst testing) you are cooling with a pressurised hose to ‘headphones’, can you leave the impeller out? I can with my elderly inboard.

I imagined the telltale to be a small visible outlet of the cooling water whilst the most of the cooling water is pumped out of the leg – often near the bevel box. Is it possible you may need to restrict the flow from the leg if you need to ensure a pressure is present at the telltale? If the R90 is to be sacrificed, how about just pumping raw sea water through it in large amounts?

Could you fit a thermocouple to each of the exhausts next to the exhaust-port? When two strokes over heat – its seems to happen too quickly for a noticeable rise in the temperature of the water jacket to act as a warning. Could save a piston or two if you’re adjusting lube and fuel.

What engine is this? Does the crank need to be dismantled to replace the centre cylinder seals or is it 2(or 3) cranks?

What is the problem with the reed valve? Is it just a flat piece of composite sheet that rests in the closed position? Are you saying it isn’t seating and you’re losing the charge back through the carb as the piston rises?

Excuse my ignorance but whats the issue with injecting a liquid premix of LPG and 2t? is it the difficulty to implement (having to empty the tank each time)? Given the amount of fuel these things drink…

If you’re concerned that the plug may be getting water across it, could you use a neon plug cap to watch the spark? What kind of magneto do you have? One source winding and three triggers or three sources? I’m assuming this is CDI rather than TCI?

Keith

[Gilbertd]

If the R90 is to be sacrificed, how about just pumping raw sea water through it in large amounts?

It would almost certainly freeze at high demand. The R90 needs heating not cooling.

[rossko]

Actually I think seawater would do fine for thermal; you're not specifically looking to heat it, just to stop it chilling down to freezing. It's only about striking a balance between temperature difference, transfer area and volume, and how much heat you're taking out by evaporation.

Oil in the LPG tank would be separated out at the point of evaporation; in this case, that's within the R90 and not at the engine's intake. And there it would puddle.

I rather think when Simon's mended the faults and restored economy that LPG won't be needed...

[kbs]

If the R90 is to be sacrificed, how about just pumping raw sea water through it in large amounts?

It would almost certainly freeze at high demand. The R90 needs heating not cooling.

Thats unlike you Gilb, that must have been one heavy night!
If the LPG boils at <-40c, the sea water at ~+15c will warm (not cool) the R90.
Suggest a high flow pump though as at that low a temp sea water, the more the better. Yes the R90 would be happer at a much higher temperature but if its the high flow type - would it not have a chance of copeing with a smallish outboard?

...Oil in the LPG tank would be separated out at the point of evaporation; in this case, that's within the R90 and not at the engine's intake. And there it would puddle..

Indeed, just like the thick oil left in my evap when dismantled.
Thats why I asked about mixing oil in the tank and injecting liquid LPG (I understand there are a few systems that offer this now - any one done one yet?). I appreciate that an extra pump is needed for this but it would also remove the need for the evap perhaps?

[Gilbertd]

If the LPG boils at <-40c, the sea water at ~+15c will warm (not cool) the R90.

I doubt Cardigan Bay is going to be that warm, even the Med drops to 13 degrees over winter and at this time of year it's only just starting to warm up. It takes a good few weeks of decent hot weather before it starts to rise to anything remotely warmish and that's a sea surrounded by land and not that deep. Cardigan Bay is joined to the Atlantic so never will get up to what I consider swimable temperatures. I'm only going on my experience with the Range Rover Classic that, despite a decent proportion of anti-freeze, would freeze the vap within 300 yards of leaving home during the winter if I gave it any welly.

In all honesty, I would say it is going to be far easier to repair the engine and run it on petrol. There's going to be a lot of experimentation and even then there's no way of knowing it's getting sufficient lubrication arriving in the right places. I wouldn't take a boat out to sea with an engine that was an unknown quantity unless I had at least a second motor to get home on. The 5.5m RIBs we used to have at work had a 50 hp outboard and a little 5 hp standby just in case.

[LPGC]

I rather think when Simon's mended the faults and restored economy that LPG won't be needed...

Well, I do think it will give a lot better economy even on petrol when I've done... Still, as an LPG installer, it would nark me that one of my vehicles wasn't running on LPG even if it is a boat! Would still expect only a couple of miles per gallon out of the thing so an LPG conversion would pay, particularly if made up from old bits I have laying around - as long as the engine gets it's bearings and bores lubed ..

An update: I haven't removed the exhaust cover yet, I'm now thinking that the bottom plug may be getting washed with fuel rather than water, I think the bottom of the 2 carbs is flooding fuel into the engine through the bottom of the 2 reeds, this also accounting for the 3 plugs getting progressively hotter towards the top of the engine according to my finger and tongue (with plugs removed) test! I'm thinking the top cylinder is getting OKish mixture, middle rich, bottom flooding and not firing. I read on another forum that this engine is particularly difficult to get idling properly, the same seemingly knowledgeable guy said he uses an infrared heat detector to measure plug temps with the engine running, (hotter plug meaning leaner mixture), the twin carbs respectively affecting mixture of the cylinder they're closest to with the middle cylinder getting a mixture somewhere between the 2 carbs output - It's a weird setup with 2 carbs feeding 2 reeds feeding 3 cylinders... I had it running on all 3 just above idle the other day (nearly cured bottom cylinder misfire altogether) by screwing the idle mixture screw all the way in on the bottom carb. This was with the cooling water disconnected, so would rule out water getting into the mix, but the plugs seemed to respond the same anyway, i.e. the bottom plug didn't look any different without the water attached. I had limited time after work but with the engine already quite hot and it getting dark I didn't want to connect the hosepipe for fear of cracking the block or exhaust housing. I'm fairly satisfied that it isn't water getting into the cylinder causing the problem - good!

I doubt Cardigan Bay is going to be that warm

My thoughts entirely when I read +15c, I wish! But as Rosko said the reducer might work OK flow from Cardigan Bay went through it. Out of the question though, I wouldn't have a way of tapping into a sea water feed with enough flow, not from the engine anyway (nowhere to tap enough flow and even if there was this would reduce flow through the engine and these motors have borderline cooling ability as it is).. could maybe install an electric pump but then the problem would be powering it, the engine only has low amp charging ability (little coil with a rectifier block), no alternator.

I wouldn't take a boat out to sea with an engine that was an unknown quantity unless I had at least a second motor to get home on.

Me neither, would take it for a few extended trips up the Ouse through York to test it first like I did when running it in after the rebuild.

Far from an expert on 2 strokes, I understand the principal for the most part but really don't like the haphazard nature of how they work and the less than smooth running even when running perfect - not to mention the smoke (that I seemed to have forgotten about since dad had his last 2 stroke outboard), makes a nice change to work on one though and I now see it as a bit of a challenge to get it running like new, also seems worth getting it there as the bottom end of the engine is for all intents and purposes new. Strange that idle speed is affected as much by ignition timing (which is retarded i.e. after TDC at idle) as throttle stop position and mixture, it all seems very inefficient to me before we even talk about 2 strokes pumping a third of the fuel straight out the exhaust .

I think I'm getting a bit more insight into the problem now though and hopefully starting to put the picture together - I rebuilt the engine because the pistons and bores were scored, rings had broken on the bottom cylinder (fitted new oversize pistons / had the bores machined / new needle bearings etc [pain!]), top cylinder was detonating fouling the plug with bits of metal... I'm now working on the assumption the top cylinder was running lean, bottom cylinder riching out and misfiring therefore getting the 50:1 mix under-lubing the bottom cylinder bore instead of the oil dropping out and lubing the bore properly. Having a problem locating a carb rebuild kit that contains the float though - can't remember if I mentioned above that apparently the original floats were not ethanol proof and may therefore sink and allow the carb to either overfuel in the conventional sense or overfuel by allowing fuel to flow out the float chamber vent.

By the way, when I said a trip across Cardigan Bay I only meant across a small part of it, from Shell Island near Harlech to Abersoch, I think it's about 12 miles over water and never more than 6 miles from shore with land on 3 sides in a sheltered bit of Cardigan Bay - far enough across sea on a small speedboat though! I do have a second smaller engine, a 5hp that was on dads tender but there's no where to mount it on the speedboat. When dad knew he was dying we were messing with something in the garage and we had to move the little engine out the way. He told me 'If you ever use that engine, bear in mind in quickly overheats, I never got to the bottom of it but I reckon you would'. I made a point of it, took the kids up the river on his old tender but it overheated despite my fitting a new water pump. I stripped the engine a bit and found loads of @!## blocking the coolant holes on the block, it's been fine since.

I'm not sure what new systems etc you mean KBS, no system could work with oil in the bottom of the LPG tank... I missed some of your questions earlier, out of those that I remember - there is a magneto type charging coil which also powers the ignition system, no points but uses 'Mercury Thunderbolt' ignition which comprises a 3 position trigger sensor under the flywheel and their OEM electronic ignition driving discreet coils with plug leads, apparently a good and reliable system and seems to be working OK. Only a bit of water comes out the tell tale, the rest goes either out the exhaust which is vented through the middle of the prop or through a couple of odd shaped outlets at the top of the leg, there seems to be no place I could tap into that system other than getting water out the block where it is at least under pressure. The 2 reed valves are mounted directly on the crank, the powerhead would have to come off to change them but apparently I can inspect them with the carbs off using a dentist mirror. Later engines use easily accessible reed valves mounted directly behind the carbs, I previously thought about adding this type if mine seemed to be broken but I think it would be easier just to replace like with like, to add the newer type reeds would mean making some sort of manifold to incorporate the reeds, this would space the carbs away from the crank case and mean re-designing the throttle system - the throttle level operates a long cam which slides in the block and moves a follower on the top carb which is on the same shaft as the throttle arm for the bottom carb.

Bad but funny things that have happened so far... Engine suddenly cut out while 400 yards out on the sea, son gets fishing tackle going while I'm removing the plugs to check for a spark and starting to feel a bit sea sick in the bent over position. 'If those people on nearby boats see you fishing, do you think they will guess we have broken down and come to help or do you think they will think we've stopped to do a bit of fishing Ed?'. 'Ahh yes, I'll put the fishing rod away dad'. Took me half an hour to get it going during which we were drifting closer to the rocky shore... Next day I was stood chest deep in water, Ed and his mate already in the boat me doing all the work and I reached in to start the engine... massive pulsing electric shock! I found out very soon than some previous owner had twisted wires together in the engine control box with insulating tape - the wires had corroded, insulating tape had worn through, bare wires to the magneto touching the unearthed metal control box housing supposedly at 110v.. Had just been having a nice chat with a very polite and well spoken family when all of a sudden I had to let it go 'Argh you b%%^%&&' but then had to regain composure quickly to prevent the engine over-revving, quick choice another shock or let the engine blow... I decided to take the shock route 'f^%&^* b%^&*^*' Hardly surprisingly I fixed the wiring first job...

The engine was produced in Belgium and in the States, my serial number was produced in Belgium. Marinas / chandlery's in this country, in fact I would say in Europe, seem a bit of a farce when you're looking for parts, they will sell you a new boat or engine but don't seem to stock anything much more in terms of parts than water pump impellors even for newish engines so I have to buy from the States and pay import duty etc... hence why I've been trying to make sure I know what parts to buy next. For example, overfuelling the bottom cylinder is likely the carb but could also be a hole in the fuel pump diaghpram letting fuel into the crankcase, unlikely because I fitted a new diaghpram and gaskets when rebuilding it, but would give the same symptoms and is very difficult to check without damaging the diagphram, the fuel pump works on pulsing pressure from the crankcase and would cost another £40 or so to change that part again... will rebuild the carbs first and take to the river, maybe take a second battery and fill the carbs from an electric lift pump to rule out the engine fuel pump in case the carb rebuild doesn't sort it. 1 Carb and 3 cylinders or 3 carbs and 3 cylinders with 3 coils in both cases would seem simple to sort and setup but this 2 carb 3 cyl setup seems a bit of a fiddle in my own and seemingly a lot of others experience.

Simon

[Gilbertd]

Next day I was stood chest deep in water, son and his mate already in the boat me doing all the work :roll

Simon, hasn't anyone told you yet? It isn't possible to bump start a boat.......

Mind you, I do recall nearly wetting myself at Rutland water a few years ago. It was the middle of summer and the water level had dropped. So much so that the keel of a yacht was wedged against the mud in the bottom so it wouldn't move and the owner was trying to push it off the mud. Only problem was, he was standing in the tender, which wasn't sitting in the mud, while trying to push it......

[LPGC]

.

Next day I was stood chest deep in water, son and his mate already in the boat me doing all the work :roll

Simon, hasn't anyone told you yet? It isn't possible to bump start a boat.......

Mind you, I do recall nearly wetting myself at Rutland water a few years ago. It was the middle of summer and the water level had dropped. So much so that the keel of a yacht was wedged against the mud in the bottom so it wouldn't move and the owner was trying to push it off the mud. Only problem was, he was standing in the tender, which wasn't sitting in the mud, while trying to push it......

Wasn't expecting a bump start but would have been nice if they'd offered to drive the car and pull the trailer off the slipway then park it up and/or hold the boat while I got the engine started and warmed up, instead of them trying to avoid the need to remove shades or getting wet feet by climbing into the boat over the front

What you said just reminded me of another situation involving mud.. At 14 I was at Shell Island with dad and his uncle. There were JCBs digging the estuary out and dads boat (19ft with 3L volvo inboard tripple carbs) was moored in the middle of this really thick mud. I was already safely on the boat, dad and uncle were trying to wade out to it with the tide about to start coming in. They both sunk to chest height in the mud and were getting well and truly stuck, try as I might to throw them a line in a fairly serious situation, I struggled because I was laughing too much!

That boat, only 19ft, only 3L engine, had a 100 gallon tank and it would have been entirely possible to use the 100 gallons in a day giving it some stick, despite the engine being well set up with us balancing the carbs and doing a colour tune etc.... Just goes to show that boats use a lot of fuel, they have a lot of drag, 200+bhp might get you doing 145mph at 5mpg on the motorway but when you're only doing 35mph flat out with the same engine in a boat you're only doing 1mpg and that's with a 4 stroke... If I do the 24 mile round trip in my boat in flat seas doing 2mpg at 35mph with the 2 stroke that's 12 gallon used, a similar amount of fuel that most car owners would expect to take them 400 miles, even in the people carrier I would expect 12 gallons to get me into Cornwall from here in Yorkshire... The type of economy that cries out for an LPG conversion especially if you have the bits around and especially if there's pro pride poking you to convert it! I do much prefer 'proper' engines, 4 strokes at least, a sewing machine straight 6 or burbling V8 would be great, even a 4 pot sounds better than any 2 stroke but 2 strokes have a weight saving and are at least designed for the job. The problems I've seen with car engines in boats have had little to do with the engine itself, they have been mostly drive/leg related and cooling system (water jacket exhaust manifold) related. I've seen people on holiday waste the whole time trying to sort problems but had to go home and wait for expensive parts to arrive - marinising parts such as water jacket manifolds particularly expensive, where outboards seemed not to suffer problems to the same extent, parts easier to get hold of and cheaper.. but now I'm having second thoughts! Last year I nearly bought a 19ft bowrider with 4.6 V6, if it had been a 5.7 V8 for the same price I would have bought it.

Watched Mr T's Crazy Fools on TV the other day. Was a story about a woman who bought a big new boat somewhere in the States but was having problems with it's performance. She complained to the marina where she'd bought it and they sent a diver out to see if there was a problem underneath because a rope from the front seemed to be stuck tight on something, maybe stuck around the prop.. Underneath he found the problem alright, the rope was still attached to the trailer winch and the trailer was still attached to her car, both underneath the boat!

Not had chance to have another mess with the 2 stroke but the next step is to get hold of carb repair kits anyway...

Simon

[LPGC]

Hopefully will be able to order the carb bits today

Spent ages yesterday collating part (and supersede part) numbers, trawling the net, speaking to suppliers in the UK and USA. It became seemingly obvious that all the UK suppliers would be ordering the parts from a single importer because they all told me they could supply 2 carb rebuild kits but only 1 float. Prices quoted from UK suppliers were all within aroud 10% of £200 for the bits.

One of the US suppliers sells bits on Ebay, I thought I'd found the correct set on one of their listings (no part numbers in this case but a reference number that I'd seen on another site seemed to match up and the parts in the Ebay pic looked correct), this kit contained the float... Great! But the listing had a footnote saying in case of some parts Mercury restrict sale outside the US, so I phoned the US supplier to check they would ship this Ebay item to the UK and confirm if was the correct kit.. On checking my engine serial number the sales guy told me I was looking at the wrong kit but they had the right kit in stock, told me another kit part number to check on Ebay... While still on the phone I found this listing but there wasn't a picture, so I asked him to check the kit contained the float - it didn't, but they had floats in stock. So I asked him to send me 2 carb repair kits and 2 floats, gave him my card details and thought job done (just wait for the parts coming)..

Later in the day a guy in the UK who I'd spoken to in the morning got back to me 'we can get those bits to you in 3 days, price £100. 'Ahh I've got some coming now about the same price from the States but thanks for your help anyway'.. Later still I got an email from the US firm 'We haven't charged your card because we checked again and the parts we thought you wanted were wrong, the parts you originally thought were right were correct, get back to us if you still want the parts'. So this morning I phoned the UK guy again and he said 'Price I told you might have changed now, I will phone you back with a price at dinner time'. Still waiting...

Simon

[Bailes1992]

Do 4 strokes actually use much less fuel compared to 2 strokes out on the water?
I imagine you'd have to have double the size for similar outputs.

[LPGC]

Without checking I think this engine is about 850cc and supposedly makes 70bhp. This is a 1982 model so might be about on a par with a 1600cc 4 stroke in terms of bhp back in it's day. I think 4 strokes are more economical, 2 strokes will always pump some of the fuel un-burned out the exhaust and in experience boats of similar size with 4 strokes (compared to 2 strokes) and similar drive (prop not jet) have always seemed more economical. Then again, the basic design of these outboards goes back to the 50's with only fairly minor changes over the years up to '82. I supposed a 4 stroke from the same ear wouldn't be great on fuel either. My mate reckons his 15ft boat with 3litre inboard would do better on fuel than the similar size boat he had with a less powerful 2 stoke. Interestingly with these outboards, sometimes engines from the same manufacturer, same year and same capacity have different bhp ratings, can only be due to the porting. I think is such cases I would rather have one that has the lowest bhp rating for it's capacity, expecting it to have the flattest torque curve and/or run smoother than the more highly strung variants.

Forget to mention a funny moment with the US supplier the other day... when I asked if the kits contained a new main jet I was asked what altitude I would be using the boat at. I told him since I'm in the UK and will do most boating on the sea anyway, altitude would be sea level.. we don't have many glacial lakes here hehe!

Bit more of an update, I've now got as far as putting my order in with the UK guy I spoke to yesterday morning and tea time at a marina in Scarborough. This guy seems the most knowledgeable and confidence inspiring of all in the UK I've spoken to (similar to the US suppliers I've spoken to), pointed me to carb diagrams etc on the net (had already found them and have the manual anyway but wanted to make sure we were on the same page...). Instead of getting parts from the same UK importer as the other suppliers apparently were he is having them delivered directly to me from Mercury in Belgium (who wouldn't supply me direct).. reckons I should get the parts tomorrow or latest Thursday. Besides the 2 carb rebuild bits and 2 floats I ordered a spare fuel pump diaphragm and impellor just in case. I might get time later to remove and strip the carbs.

Simon

[kbs]

Does the engine have reed valves mounted in the crankcases or disc valves mounted on the crank?
Unless these are on the crankcase and have been exchanged for 'high performance' types then failiure seems unlikley.

Has anyone looked for average sea temperatures there?
I think you'll be surprised.
20 degrees still counts as "*&%^* cold!!" if you jump in.
I've unfouled props at ~15 and you start to lose the feelings in your fingers after a few minutes.
I was in the Adriatic a few weeks back and noticed that was bearly warmer.
In Bristol Channel the incoming water temperature on my boat stays near to 15 even at the end of the winter, it may be a degree or two off though.

If warming your evep with it, a big pump to move lots of water - as Gilb mentions, if you only had a very small resevoir (like a cars cooling system) the 15 degree water would soon drop to a freeze. Fortunatly the Irish Sea holds a little more water than a P38 (even after its be raining for two days).

Have pity on me.... after 7 years the old Vectra is finally getting its own way and is being scrapped due to injector failiures.

I'm posting on the wanted section in case I can find an older cheapy LPG in the south, if not, time for another conversion.

K

[LPGC]

Another update...

UK supplier sent me the correct floats, pump diaphragm and impellor but sent on;y carb gasket sets instead of repair kits. I had already stripped the carbs waiting for the bits, carbs and floats seemed OK but on one carb float height was very wrong.

I put the carbs together setting correct float height and using the new gaskets, will be returning the floats since the thing that clinched the deal was the low price of the repair kits that they got wrong (floats from here much more expensive than from the US - can get full repair kit including floats for less from there..).

Got it running in the yard OKish, idling on all cylinders but with the bottom carb mixture screw much further in than the top carb (top carb open 1.5 turns from seat as suggested in manual, bottom carb seeming to flood bottom cylinder if open more than 3/4 turn). Suspecting the fuel pump diaghpram at this point, so I installed the new one (gasket broke on old one during removal) with no effect. Still, seeming to run OK but with difficult starting. These carbs don't have a choke flap, they have a solenoid operated on/off enrichment device, effectively another jet which turns in a shaft to either supply either extra fuel or air depending on which way it's pointing. I'm sure these are working properly but still the hard starting...

Did the above without running the engine in water (not letting it get too hot though) to rule out water finding it's way into the cylinders. Still, this damaged the impellor, so I fitted the new impellor and tested it again but this time in water, water made no difference, I don't think any water is getting into the pots.

Took it to the river today (Sun) to try it, hopefully set it up (timing / mixture etc - all these are part of 'synchronisation' in 2 stroke outoard terms. Had a hell of a job starting it at the river - in the yard I'd flattened the boat battery so used jumper cables from my car with car engine running, so in the yard the engine turned over quicker and was easier to start.. Got it started and idling nicely but only for a few minutes at a time despite having a good play with idle throttle, mixture screws and ignition timing. Didn't even get it into gear so couldn't try setting it up for idle in gear, didn't have confidence in it to go for a ride - I reckon it would have been OK under throttle but I couldn't risk it stranding me, the point of going to the river today was to try and set it up anyway!

KBS - I Never managed to inspect the read valves, they are on the crank and I too doubt they're the problem - though I did tamper with them a bit when I rebuilt the engine. Was hoping to be able to inspect them using a dentist mirror with the carbs off but wasn't possible. I don't think they'll be part of the problem because I did manage to get a fairly smooth idle at fairly low rpms... sometimes!
I had a look at sea temps for Harlech on a site called Surf Watch, you weren't far off with 15c! Site says 13.5c sea temp there today, I'm surprised at that.
Poor old Vectra!

When I next get time I might switch the carb positions (even running smoothly on 3 pots the top pot seems to be doing most of the work followed by the middle pot), this would rule out anything to do with fueling such as carb throttle position, mixture, reed valves / take the inlet cover off, have seen a bit of oil below the cover and thinking it might have come out it so maybe there's a leak there that could let air and fuel in/out / check the ignition thoroughly - seemingly a good spark to all 3 but I'll check how far sparks can jump and for multi sparks per rpm (shouldn't happen but can with certain faults).. could be a problem with the triggers etc.

Simon